Clot retrieval catheter

ABSTRACT

A clot retrieval device, for example to be used in a thrombectomy, is provided including a catheter, an elongated member, and a knitted basket with a proximal end coupled to the catheter and a distal end coupled to the elongated member. The elongated member is movable between an expanded position and a compressed position relative to the catheter and is configured so that the knitted basket expands radially and compresses as the elongated member is moved to the compressed position. The knitted basket is comprised of a plurality of wires coupled together by a plurality of windings. Each winding comprises one of the plurality of the wires twisted about another of the plurality of wires.

CROSS REFERENCE

This application is a continuation of and claims priority to U.S. patentapplication Ser. No. 14/842,268 filed on Sep. 1, 2015, which is herebyincorporated by reference. U.S. patent application Ser. No. 14/842,268is a non-provisional application claiming priority to U.S. ProvisionalPatent Application No. 62/044,512 filed Sep. 2, 2014. Which is alsohereby incorporated by reference.

BACKGROUND

The field of the present invention relates to devices to remove athrombus from an intraluminal passage. Intravenous devices are commonlyused during thrombectomies to remove a thrombus from blocking blood flowthrough an intraluminal passage. Frequently, an aspirator is brought tothe blockage area to collect the thrombus by suction. However, aspiratorcatheters typically have a large cross-section and may be difficult touse in narrow intraluminal passages, particularly within the brain.

In such procedures, it is desirable to retrieve the thrombus or embolismand bring it to a wider area of the intraluminal passage for removal byan aspirator catheter. Several devices exist to accomplish this purpose,such as a wire within a catheter which deploys into a coil. However,these devices are difficult to maneuver to the desired intraluminalpassage because of the tortuous angles within such area of vasculatureand because the devices cannot be adequately steered to the site of thethrombus. Additionally, often the thrombus cannot be adequatelycontained within the device during retraction. If the thrombus fragmentsor escapes from the device during retraction, the thrombus or a portionof the thrombus may cause a blockage elsewhere in the vasculaturecausing significant harm to the patient.

It is desirable for a clot retrieval device to exist which has a smallcross-sectional profile which can also be adequately steered to the clotwithin narrow intraluminal passages. Furthermore, it is desirable thatsuch a device be capable of adequately capturing and containing the clotduring retraction through the intraluminal passage.

SUMMARY

Further areas of applicability will become apparent from the descriptionprovided herein. It should be understood that the description andspecific examples are intended for purposes of illustration only and arenot intended to limit the scope of the present disclosure.

In one form of the present disclosure, a clot retrieval device isprovided comprising an outer catheter comprising a distal end and alumen through the distal end. The device further comprises an elongatedmember comprising an outer surface and a distal portion. The elongatedmember is configured to pass through the at least one lumen of the outercatheter and is movable relative to the outer catheter between anextended position and a compressed position. The device furthercomprises a knitted basket comprising a proximal end coupled to thedistal portion of the elongated member. When the elongated member is inthe extended position, the knitted basket is adjacent to the outersurface of the elongated member. When the elongated member is moved tothe compressed position, at least a portion of the knitted basketexpands radially from the outer surface of the elongated member. Theknitted basket is comprised of a plurality of wires coupled together bya plurality of windings comprising one of the plurality of wires twistedabout another of the plurality of wires.

In another form of the present disclosure, a clot retrieval device isprovided comprising a catheter comprising a proximal end, a distal end,and a lumen through the distal end. The device further comprises anelongated member comprising an outer surface, a lumen, a proximal end,and a distal portion. The elongated member is configured to pass throughthe lumen of the catheter and is movable relative to the catheterbetween an extended position and a compressed position. The devicefurther comprises a wire guide configured to pass through the lumen ofthe elongated member, and an expandable knitted basket comprising aproximal end coupled to the distal end of the catheter and a distal endcoupled to the distal portion of the elongated member. The devicefurther comprises an actuator comprising a first member coupled to theproximal end of the elongated member and a second member coupled to theproximal end of the elongated member. The actuator is configured to movethe elongated member between the extended position and the compressedposition.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

The invention may be more fully understood by reading the followingdescription in conjunction with the drawings, in which:

FIGS. 1A-1C are side plan views of a clot retrieval device, showing anouter catheter, an inner elongated member and a knitted basket;

FIGS. 2A-2C are side plan views of a clot retrieval device, showing thedevice in an intraluminal passage alongside a thrombus;

FIG. 3 is a partial cross-sectional view of a clot retrieval device,showing an outer catheter, an inner elongated member, and a knittedbasket which transitions to a several pairs of helical wires;

FIGS. 4A-4G are side plan views of knitted baskets, showing severalpossible configurations for the structure of a knitted basket;

FIG. 5A is a close-in, plan view of a knitted basket, showing a windingbetween two wires.

FIG. 5B is a close-in, plan view of a twisted pair of wires in acontinuous twist.

FIG. 6A is a side plan view of a clot retrieval device, showing an outercatheter, an inner elongated member, and a knitted basket which includesproximal and distal coverings;

FIG. 6B is a cross-sectional axial view of a clot retrieval device,showing an inner elongated member, a plurality of wires and a foldedcovering;

FIG. 7 is a side plan view of a clot retrieval system, showing anintraluminal passage, a thrombus, a clot retrieval device, and aninflatable aspirating sheath;

FIG. 8 is a partial cross-sectional view of a clot retrieval device,showing a plurality of knitted baskets, an outer catheter, an innercatheter, and an elongated member;

FIG. 9A is a side plan view of an actuator for a clot retrieval device,showing the movement of a button in relation to a casing;

FIG. 9B is a cross-sectional view of an actuator for a clot retrievaldevice, showing a button within a slot, and a sledge;

FIGS. 10A-10D are partial cross-sectional views of an actuator for aclot retrieval device, showing the method of operation between an outerslidable member and an inner slidable member.

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present disclosure in any way.

DETAILED DESCRIPTION

Referring now to the drawings, and particularly to FIGS. 1A-1C, a clotretrieval device 22 is shown comprising a catheter 10 having at leastone lumen 38 through the distal end 34 (shown in FIG. 3), an elongatedmember 16 which is configured to pass through the lumen 38 of thecatheter 10, and a knitted basket 14 having a proximal end coupled tothe distal end 34 of the catheter 10 and a distal end coupled to thedistal portion 18 of the elongated member 16.

The elongated member 16 is movable relative to the catheter 10 between alongitudinally extended position (shown in FIG. 1A) and a longitudinallycompressed position (shown FIG. 1C). In the extended position, thedistal portion 18 of the elongated member 16 is farthest from the distalend 34 of the catheter 10. In the compressed position, the distalportion 18 of the elongated member 16 is closest to the distal end 34 ofthe catheter 10. When the elongated member 16 is in the extendedposition relative to the catheter 10, the basket 14 is adjacent to orrests on the outer surface of the elongated member 16. As the elongatedmember 16 moves to the compressed position relative to the catheter 10,the basket 14 expands radially from the outer surface of the elongatedmember and compresses in length.

The distal portion 18 of the elongated member 16 may also include anatraumatic tip 20. This atraumatic tip may take the form of a simplerounded end, as shown in FIGS. 1A-1C or in the form of a flexible,floppy tip. The atraumatic tip 20 ensures that the device 22 may be usedin a narrow intraluminal passage 28 without damaging the walls 26 of theintraluminal passage 28.

The elongated member 16 may also comprise a braid within the interior ofthe elongated member 16. The braid within the elongated member 16 maycomprise Nitinol wire and extend the entire length of the elongatedmember 16 or may be included only in the portions of the elongatedmember 16 which are configured to extend beyond the catheter 10. Thebraid may extend into the distal portion 18 of the elongated member andmay be connected to a portion of the wires 32 extending into the distalportion 18 by twisting, braiding, or welding.

The device 22 may also comprise a collar 12 coupled to the elongatedmember 16 so that, when the elongated member 16 is in the compressedposition, the collar 12 is adjacent to or rests against the distal end34 of the catheter 10. The collar 12 may be sized to be larger than thelumen 38 of the catheter 10 so that the collar 12 cannot be retractedinto the catheter 10. When the collar 12 is moved against the distal end34 of the catheter 10, the elongated member 16 may be prevented frombeing proximally moved beyond the compressed position. Alternatively,the collar 12 may take the form of any other projection which wouldprevent retraction into the lumen 38 of the catheter 10.

Additionally, the collar 12 may be used to monitor the positions of theelongated member 16 and the basket 14 using radioscopy. The device 22may also comprise two radiopaque markers at the proximal and distal endsof the basket 14 to show the position of the basket within theintraluminal passage 28. The proximal marker may be coupled to thedistal end 34 of the catheter 10 and the distal marker may be coupled tothe distal portion 18 of the elongated member 16. When the elongatedmember 16 is moved towards the compressed position, the movement of themarkers may be observed through radioscopy to indicate the position ofthe elongated member 16 relative to the catheter 10. If the collar 12 isalso radiopaque, the operator may observe that the elongated member 16is in the compressed position when the collar 12 is adjacent to theproximal marker.

Alternatively, a portion of the elongated member 16 may be comprised ofa radiopaque material and used in conjunction with the markers todetermine the positions of the elongated member 16 and the basket 14using radioscopy. When the elongated member 16 is in the compressedposition, and the basket 14 has been radially expanded, a portion of theelongated member 16 is exposed and outside of the catheter 10. Thisportion of the elongated member 16 may be made of a radiopaque materialso that the operator may observe that the elongated member 16 is in thecompressed position when the radiopaque portion of the elongated member16 is adjacent to or overlapping with the proximal marker.

As another alternative, all or a portion of the wires 32 comprising theknitted basket 14 may be made from a radiopaque material, may have aradiopaque core, or may have a radiopaque coating applied to the wire32. The radiopaque material may be platinum, gold, iridium, or any otheralloy which is opaque to under radioscopy, such as DFT Wire manufacturedby Fort Wayne Metals. A single wire 32 or a plurality of wires 32 in theknitted basket 14 which are radiopaque may ease the ability of anoperator to position and operate the clot retrieval device 22 whileusing radioscopy.

The device 22 may also comprise at least one support wire 24 having afirst end coupled to the elongated member 16 and a second end coupled tothe basket 14. The first end is arranged proximally to the second end sothat, as the basket 14 expands radially, the support wire 24 willcontribute proximal force to the knitted basket 14, assisting incompressing the length of the basket 14 evenly as the basket 14 expandsradially. More than one support wire 24 may be desired depending on thelength of the basket 14.

Referring to FIGS. 2A-2C, a possible embodiment of the clot retrievaldevice 22 is shown within an intraluminal passage 28. FIG. 2A shows thedevice 22 with the elongated member 16 in the extended position, withthe knitted basket 14 adjacent to the outer surface of the elongatedmember 16. In this position, the device 22 can more easily be positionedwithin the intraluminal passage 28, and can pass through or around thethrombus 30 or blockage.

As shown in FIG. 2B, once the distal end of the elongated member haspassed through or around the thrombus 30 so that the knitted basket 14overlaps at least a portion of the thrombus 30, the inner elongatedmember 16 is moved to the compressed position. As the knitted basket 14begins to expand radially in response to the movement of the elongatedmember 16, the wires 114 that comprise the knitted basket 14 passthrough or around the thrombus 30 and may reach the walls 26 of theintraluminal passage 28.

As shown in FIG. 2C, once the elongated member 16 is in the compressedposition and the knitted basket 14 has been fully expanded, the thrombus30, or a portion of the thrombus 30, will be contained within theknitted basket 14. From this configuration, the clot retrieval device 22may be retracted to remove the thrombus 30 from the intraluminal passage28.

Referring to FIG. 3, a partial cross-sectional view of the clotretrieval device 22 is shown. In this embodiment, the knitted basket 14is comprised of a plurality of wires 114 which are embedded in both thecatheter 10 and the distal portion 18 of the elongated member 16.Although it is not readily apparent from the illustration of FIG. 3 thatthe wires 32 are formed into helical wires 32 in a continuous braidedtwist within the catheter wall 36 and the distal portion 18 of theelongated member 16, it is preferable for the helical wires 32 to bebraided or twisted together within these embedded portions. Furthermore,the wires 32 embedded in the catheter wall 36 spiral around the catheter10 as shown in FIG. 3. Between the distal end 34 of the catheter 10 andthe distal portion 18 of the elongated member 16, the wires 114 extendin a knitted pattern to form the knitted basket 14, although theknitting of the wires 114 may not be apparent from the embodiment shownin FIG. 3. Although the embodiment shown in FIG. 3 shows only twohelical wires 32, the clot retrieval device 22 may have many helicalwires 32 which separate to be integrated into the knitted basket 14.Alternatively, the wires 114 may be embedded within the catheter 10without twisting, simply wrapping around within the walls 36 of thecatheter 10 to the distal end 34 where the knitted basket 14 begins. Thehelical wires 32 are distinguished from the wires 114 in the knittedbasket 14 in that the helical pairs 118 of wires 32 are continuouslybraided or twisted together so as to be adjacent to one another, neverseparating until transitioning to individual wires 114 to beincorporated into the knitted basket 14. Within the walls 36 of thecatheter 10, it may be desirable for the wires 32 to extend the entirelength of the catheter 10, from the proximal end to the distal end 34 ofthe catheter 10.

The wires 32 may have three stages of interaction depending upon theirposition along the catheter 10. Within the catheter 10, the wires 32 maybe configured in a first stage comprising a braid, crossing over andunder one another in as they circle about the catheter wall 36. Thewires 32 in this first stage may have a flat cross-sectional shape toreduce their cross-sectional area. As the wires 32 extend from thedistal end 34 of the catheter 10, but before the knitted basket 14, thewires 32 may be configured in a second stage comprising a continuoustwist (Example in FIG. 5B, Reference Number 162). If the cross-sectionalshape of the wire 32 changes between the first and second stage of thewires 32, the wires 32 may be welded together inside or outside thecatheter 10. If the catheter 10 includes a radiopaque marker at thedistal end 34 of the catheter 10, the wires may transition from thefirst stage configuration to the second stage configuration under theradiopaque marker. The wires 32 are also configured in a third stagecomprising the knitted basket 14. The wires 32 may return to the secondstage configuration and first stage configuration as the wires 32 extenddistally beyond the knitted basket 14 and into the distal portion 18 ofthe elongated member 16.

The distal portion 18 of the elongated member 16 may have a differentdiameter and may be made of a different material than the rest of theelongated member 16. For ease of manufacture, it may be desirable thatthe distal portion 18 of the elongated member 16 have a similar diameteras the catheter 10. If the distal portion 18 is a different diameterthan the rest of the elongated member 16, then the elongated member 16may be embedded within the distal portion 18 to secure it in place.

The catheter wall 36 may comprise an inner layer which defines the lumen38 of the catheter 10. The inner layer of the catheter wall may comprisea material such as PTFE. The wires 32 formed in a braid may bepositioned on this inner layer. Additionally, a polymer may be appliedto the inner layer and the wires 32 to form the outer surface of thecatheter 10. The polymer may cover the first braided stage of the wires32 entirely, filling in any gaps which may exist within the braid.

In FIGS. 4A-4G, eight possible embodiments of the knitted basket 14 areshown. These embodiments in no way comprise a complete list of possibleembodiments, but only illustrate how various embodiments of the knittedbasket 14 may be configured. All of the embodiments of the knittedbasket 14 shown in FIGS. 4A-4G share some common elements. The knittedbaskets 14 comprise a plurality of helical pairs 118 of wires 114 on theproximal and distal ends of the knitted basket 14. These helical pairs118 comprise a continuous wrapping of the two component wires 114 aroundeach other. Between the proximal and distal ends of the knitted basket14, the helical pairs 118 of wires 114 separate into individual wires116 which are integrated into the structure of the knitted basket 14. Inthe knitted basket 14, a individual wires 116 separate so that each wire114 forms a series of interconnected windings 106. The interaction ofthese wires 114 form empty cells 110, 124, 130, 140, 148, 149 having acell width 104, 122, 128, 138, 146, 152 when the knitted basket 14 is inits radially expanded position.

Each cell is comprised of four wires 114, a first pair 164 and a secondpair 166, and four windings 106, a first winding 168, a second winding170, and two side windings 172. The designation of each of the wirepairs 164, 166 and windings 106 are entirely dependent upon theindividual cell 110, 124, 130, 140, 148, 149. A first pair 164 for onecell 110, 124, 130, 140, 148, 149 will form the second pair 166 for adifferent cell 110, 124, 130, 140, 148, 149. Similarly each side winding172 will also be a first winding 168 and a second winding 170 dependingon the cell 110, 124, 130, 140, 148, 149.

From the first winding 106, the first pair of wires 164 separate fromthe first winding 168 towards respective side windings 172 on eitherside of the cell 110, 124, 130, 140, 148, 149. The first pair of wires164 proceed from the first winding 168 at a first angle 102, 120, 134,136, 144 relative to the axis of the device's 22 movement within theintraluminal passage 28, a longitudinal axis. Similarly, the second pairof wires 164 converges toward the second winding 170 from respectiveside windings 172. The second pair of wires 166 converges on the secondwinding 170 at a second angle 103, 121, 135, 137, 144 relative to theaxis of the device's 22 movement within the intraluminal passage 28, thelongitudinal axis. These first and second angles 102, 103, 120, 121,134, 135, 136, 138, 144, along with the radially expanded knitted basket14 diameter 112 determines the cell 110, 124, 130, 140, 148, 149 shapeand the radially expanded knitted basket length 108, 126, 132, 142, 150,154, 156.

In determining the design of the knitted basket 14, severalconsiderations may be taken into account. For example, the radial forcethat knitted basket 14 exerts as it expands is important to ensure thatthe wires 114 are forceful enough to pass through the thrombus 30.Additionally, the size of the cells 110, 124, 130, 140, 148, 149 formedby the knitted wires 114 in the knitted basket's 14 radially expandedposition should be considered. If the cell width 104, 122, 128, 138,146, 152 is too wide, the thrombus 30 may not be contained within theknitted basket 14 during retraction. However, if the wires 114 in theknitted basket 14 are spaced too closely together, creating very smallcell width 104, 122, 128, 138, 146, 152, the thrombus 30 may fragmentduring the radial expansion of the knitted basket 14.

The length of the basket 14 in its expanded form may also be consideredto ensure that the thrombus 30 can be contained within the knittedbasked 14. The ratio of the lengths of the knitted basket 14 between itsextended position over its radially expanded position may be anotherconsideration. A high length ratio may allow for smaller cells 110, 124,130, 140, 148, 149 to better capture the thrombus 30, however theknitted basket 14 may also require one or more support wires 24 toevenly expand. A small length ratio may allow for a shorter device 22and easier radial expansion, but it may also create larger cells 110,124, 130, 140, 148, 149 by which the thrombus 30 may escape duringretraction.

The design of the knitted basket may also consider the effect of theknitted basket 14 while moving against the walls 26 of the intraluminalpassage 28. During retraction of the knitted basket 14, the device 22has a much larger cross-sectional profile as the knitted basket 14 isradially expanded. This may cause irritation or damage as the knittedbasket 14 scrapes against the walls 26 of the intraluminal passage 28.To reduce the irritation to the walls 26 of the intraluminal passage 28,it may be desirable to utilize a basket 14 with wires 114 which, whenthe knitted basket 14 is radially expanded, form cells 110, 124, 130,140, 148, 149 with wires 114 at small angles 102, 120, 134, 136, 144relative to the axis of the device's 22 movement within the intraluminalpassage 28, the longitudinal axis. Wires 114 on the knitted basket 14which are oriented at high angles or perpendicular to the movement ofthe device 22 within the intraluminal passage 28 may cause moreirritation to the walls 26 of the intraluminal passage 28.

FIG. 4A shows a knitted basket 14 wherein each cell 110 comprises afirst pair of wires 164 and a second pair of wires 166 having a firstand a second angle 102, 103 at or near 90 degrees. These angles angle102, 103 results in cell 110 shapes which are roughly rectangular andhave a very narrow cell width 104. When the knitted basket 14 isextended by the elongated member 16, the length of the knitted basket 14proximal to the elongated member 16 may be up to 200% longer than thelength 108 of the radially expanded knitted basket 14.

FIG. 4B shows a knitted basket 14 wherein each cell 124 comprises afirst pair of wires 164 having a first angle 120 at or near 55 degrees,and a second pair of wires 166 having a second angle 121 at or near 90degrees. These angles 120, 121 result in a cell 124 shape which isnearly triangular, with a wider cell width 122 than the cell 110 shapeshown in FIG. 4A. When the knitted basket 14 is extended by theelongated member 16, the length of the knitted basket 14 proximal to theelongated member 16 may be up to 90% longer than the length 126 of theradially expanded knitted basket 14.

FIG. 4C shows a knitted basket 14 wherein each cell 130 comprises afirst pair of wires 164 having a first angle 134 at or near 40 degrees,and a second pair of wires 166 having a second angle 135 at or near 90degrees. These angles 134, 135 result in a cell 130 shape which isnearly triangular, with a wider cell width 128 than the cell 124 shapeshown in FIG. 4B. When the knitted basket 14 is extended by theelongated member 16, the length of the knitted basket 14 proximal to theelongated member 16 may be up to 50% longer than the length 132 of theradially expanded knitted basket 14.

FIG. 4D shows a knitted basket 14 wherein each cell 140 comprises afirst pair of wires 164 having a first angle 136 at or near 35 degrees,and a second pair of wires 166 having a second angle 137 at or near 90degrees. These angles 136, 137 result in a cell 140 shape which isnearly triangular, with a wider cell width 138 than the cell 130 shapeshown in FIG. 4C. When the knitted basket 14 is extended by theelongated member 16, the length of the knitted basket 14 proximal to theelongated member 16 may be up to 30% longer than the length 142 of theradially expanded knitted basket 14.

FIG. 4E shows a knitted basket 14 wherein each cell 148 comprises afirst pair of wires 164 and a second pair of wires 166 having identicalangles 144 at or near 55 degrees. This results in a cell 148 shape whichis nearly diamond-shaped, with a wider cell width 122 than the cell 124shape shown in FIG. 4B but a shorter cell width 122 than the cell 130shown in FIG. 4C. When the knitted basket 14 is extended by theelongated member 16, the length of the knitted basket 14 proximal to theelongated member 16 may be up to 90% longer than the length 150 of theradially expanded knitted basket 14.

FIG. 4F shows a knitted basket 14 comprising wires 114 at varying angles120, 121, 134, 135, 136, 137 to create cell 124, 130, 140 shapes whichhaving an increasing cell width 122, 128, 138 as the cells approach thecenter of the knitted basket 14. In the embodiment shown, the knittedbasket 14 has one set of cells 124 similar to those shown in FIG. 4B onboth the proximal and distal end of the knitted basket 14. Closer to thecenter from that layer, is an additional layer of cells 130 similar tothose shown in FIG. 4C, which are wider than the cells 124 shown in FIG.4B. In the center of the knitted basket 14 is a single layer of cells140 similar to those found in FIG. 4D, which has the widest cell width138. When the knitted basket 14 is extended by the elongated member 16,the length of the knitted basket 14 proximal to the elongated member 16may be up to 60% longer than the length 154 of the radially expandedknitted basket 14.

FIG. 4G shows a knitted basket similar to that shown in FIG. 4F, whereinthe cell width 122, 128, 138, 152 increases closer to the center ofknitted basket 14. However, unlike FIG. 4F, the cells 124, 130, 140 arearranged in such a way to create large diamond cells 149 at the centerof the knitted basket 14, each having a very large cell width 152, widerthan any of the other cell widths 122, 128, 152. When the knitted basket14 is extended by the elongated member 16, the length of the knittedbasket 14 proximal to the elongated member 16 may be up to 40% longerthan the length 150 of the radially expanded knitted basket 14.

FIG. 5A shows an example of a winding 106 between wires 114 in theknitted basket 14. The configuration shown in FIG. 5 is a double-twistwinding 106, wherein the wires 114 are twisted (158, 160) around eachother twice, each wire 114 being twisted substantially 360 degrees. Eachtwist 158 alters the direction of the wires 114 substantially 180degrees. The first twist 158 alters the direction of the wire 114 andreflects its direction, while the second twist 160 maintains each wire114 along its original path prior to the winding 106. Although adouble-twist winding 106 is shown here, other number of windings 106 maybe appropriate for various circumstances. Knitted baskets 14 consistingof fewer twists in their windings 106 will use less wire 114 length andmay be more flexible. However, knitted baskets 14 with more twists intheir windings 106 may be more structurally rigid, holding their shapemore consistently in the extended and compressed forms. A high number oftwists in each winding may, however, affect the shape of the cell, 110,124, 130, 140, 148, 149, decreasing the knitted basket's 14 abilityeffectively compress and expand. As a result, it may be desirable tolimit windings to 5 or fewer twists.

Furthermore, an even number of twists in each winding 106 will result inindividual wires 114 being twisted by an angle of substantially 360degrees, 720 degrees, or some other similar angle. Such a winding 106,when repeated on the entire knitted basket 114, will result in the wires114 spiraling around the circumference of the knitted basket 14. Thisconfiguration may be desirable to give the knitted basket 14 additionalstability and to prevent collapsing or kinking during radial expansion.Alternatively, an odd number of twists in each winding 106 will resultin individual wires 114 being twisted by an angle of substantially 180degrees, 540 degrees, or some similar angle. Such a winding 106, whenrepeated on the entire knitted basket 14, will result in the wires 114reconnecting with the same individual wire 114 every other winding 106and remaining in a circumferentially stable position along the length ofthe knitted basket 14. This configuration may however be less stable andmay cause kinking or collapsing of the knitted basket 14 during radialexpansion, depending on the forces exerted on the wires 114 duringradial expansion.

Referring to FIG. 5B, an example of a helical pair 118 of wires 32 isshown in a continuous twist 162. In contrast to the winding 106 shown inFIG. 5A, the helical pair 118 of wires 32 are arranged in a continuousbraid or twist typically comprising at least 5 consecutive twists, sothat each of the helical pair 118 of wires 32 is continuously adjacentto each other. The braiding or twisting may, however, extend the entirelength of the catheter 10. The arrangement of the helical pairs 118 isadvantageous since it allows the helical pairs to take up a small amountof space while spiraling within the wall 26 of the catheter 10. Afterpassing through the distal end 34 of the catheter 10, however, thehelical pair 118 can be separated to be integrated into the knittedbasket 14. It may be desirable that the helical pairs 118 are twisted inthe same direction at the windings 106 in the knitted basket 14 toincrease the stability of the knitted basket 14 and to preventcollapsing or kinking during radial expansion. For example, if thehelical pairs 118 are twisted or braided together in a clockwisefashion, then it may be desirable to twist the windings 106 in in theknitted basket 14 in the same clockwise direction.

Referring to FIGS. 6A and 6B, another embodiment of the clot retrievaldevice 62 is shown with proximal and distal coverings 56, 58 on theproximal and distal ends of the knitted basket 14. The coverings may bemade of a thin flexible material which is compressible. The coverings56, 58 are coupled to the wires 114 of the knitted basket 14. Theproximal covering's 56 proximal side may also be coupled to thecatheter's 10 distal end 34, while distal covering's 58 distal side mayalso be coupled to the distal portion 18 of the elongated member 16.When the elongated member 16 is in the extended position, the proximaland distal coverings 56, 58 compress so that the entire cover 56, 58 isadjacent to the outer surface of the elongated member 16. When theelongated member 16 is in the compressed position, the proximal anddistal coverings 56, 58 expand radially along with the knitted basket14. The coverings 56, 58 may be configured on the knitted basket 14 sothat the portions of the coverings further from the center of theknitted basket 14 expand less than the portions closer to the center ofthe knitted basket. If the ends of the coverings 56, 58 are coupled tothe catheter's 10 distal end 34 or the elongated member's 16 distalportion 18, those ends of the coverings 56, 58 may not expand at all.While expanded, the coverings 56, 58 are effective in controlling theproximal and distal motion of the thrombus 30 which is contained withinthe knitted basket 14.

To ensure that the cross-sectional profile of the clot retrieval device62 is as small as possible, it may be desirable to include pre-set foldsinto the proximal and distal coverings 56, 58 by defining fold lines 60on the surface of the coverings 56, 58. It may be desirable to placethese fold lines 60 off-center between the wires 114 of the knittedbasket 14, so that when the elongated member 16 is in the extendedposition, the proximal and distal coverings 56, 58 fold at the foldlines in a spiral pattern, as shown in FIG. 6B.

Referring to FIG. 7, a clot retrieval system is shown which includes awire guide 21, a knitted basket 14 coupled to a catheter 10 and anelongated member 16, an aspiration catheter 96, and a sheath 98 whichincludes an inflatable member 100.

For narrow or tortuous intraluminal passages 28, it may be desirable toinitially advance a wire guide 21 to the thrombus 30 because of a wireguide's smaller cross-sectional profile and steerability. As shown inFIG. 7, the clot retrieval device 22, may configured to be advanced overa wire guide 21. To accommodate a wire guide 21, the elongated member 16may comprise a lumen. The wire guide 21 passes through this lumen sothat the clot retrieval device 22 may be advanced to the thrombus 30.

Fragmentation of the thrombus 30 during retrieval may be a risk in someoperations. To prevent fragmentation from causing complications to thepatient, it may be desirable to include an additional sheath 98 with theclot retrieval device 22. This sheath 98 may be advanced over the clotretrieval device 22, or alongside the device. If the sheath 98 is to beadvanced over the clot retrieval device 22, the sheath 98 will have afirst lumen which the device 22 may pass through.

The sheath 98 may also have a second lumen to accommodate an aspirationcatheter 96, which may use suction to collect fragmented portions of thethrombus 30 and prevent their circulation throughout the patient's body.Alternatively, the aspiration catheter 96 may also be brought inproximity of the knitted basket 14 after the capture of the thrombus 30to safely remove the thrombus 30. In this way, it would not be necessaryto maintain the elongated member 16 in its extended position during theretraction of the clot retrieval device 22.

The sheath 98 may also include an inflatable member 100 locatedproximally from the knitted basket 14. This inflatable member 100 may beinflated to block the flow of blood within the intraluminal passage 28,allowing safe retrieval of the thrombus 30 and any fragments which mayresult from its capture within the knitted basket 14. The inflatablemember 100 may be inflated by a third lumen within the sheath 98.

In some operations, it may be desirable to have multiple knitted baskets40, 42 to retrieve more than one thrombus 30. Referring to FIG. 8, yetanother embodiment of the clot retrieval device 50 is shown having aplurality of knitted baskets 40, 42. For simplicity, the bodies of thebaskets 40, 42 are omitted, however the design of the baskets 40, 42 maybe similar to any of the designs discussed above. In the embodiment ofFIG. 8, an first outer catheter 48 is shown having a second innercatheter 44 disposed within a lumen of the first outer catheter 48.Furthermore, an elongated member 46 is disposed within a lumen of thesecond inner catheter 44. The first outer catheter 48 and the secondinner catheter 44 are movable between a longitudinally extendedposition, and a longitudinally compressed position, which controls theradial expansion of the first basket 40. Similarly, the second innercatheter 44 and the elongated member 46, are separately movable betweena longitudinally extended position and a longitudinally compressedposition, which controls the radial expansion of the second basket 42.In this way, each knitted basket 40, 46 may be separately radiallyexpanded to capture different thrombi 30 or different portions of alarger thrombus 30.

The knitted baskets 40, 42, shown in FIG. 8 comprise a single set ofwires 114 which run at least from the distal end of the first outercatheter 48 to the distal portion 54 of the elongated member 46. Withinthe first outer catheter, the wires 114 are arranged in helical pairs118, which spiral within the walls of the first outer catheter 48.Distal from the distal end of the first outer catheter 48, the helicalpairs 118 separate to be integrated into the first knitted basket 40.Distal from the first knitted basket 40, helical pairs 118 are reformedand are embedded within the walls of the distal end of the second innercatheter 44. Distal from the distal end of the second inner catheter 44,the helical pairs 118 separate to be integrated into the second knittedbasket 42. At the distal portion 54 of the elongated member 46, thewires 114 form helical pairs 118 and are embedded within the elongatedmember 46. Alternatively, the first and second baskets 40, 42 maycomprise two unconnected sets of knitted wires 114, however, this mayincrease the size and cost of manufacturing the device 50.

When using the multi-basket device 50, it may be desirable to passthrough or around the first proximal thrombus with the elongated member46 and the second inner catheter 44, positioning at least a portion ofthe first proximal thrombus to overlap with the first basket 40. Thefirst outer catheter 48 and the second inner catheter 44 may be moved tothe compressed position to radially expand the first basket 40 andcapture the first proximal thrombus within. The device may then beadvanced further so that the elongated member 46 passes through oraround a second distal thrombus, positioning at least a portion of thesecond distal thrombus to overlap with the second basket 42. The secondinner catheter 44 and the elongated member 46 may then be moved to thecompressed position to radially expand the second basket 42 and capturethe second distal thrombus within. The device 50 may then be retractedto clear the intraluminal passage 28.

Alternatively, if the thrombus 30 is too large to be retrieved with asingle knitted basket 14, the multi-basket device 50 may be used so thata proximal portion of the thrombus 30 may be captured within the firstbasket 40, and the distal portion of the thrombus 30 may be capturedwithin the second basket 42. Similar designs could be used providingadditional baskets to retrieve a larger thrombus 30 within a narrowintraluminal passage 28.

Referring to FIGS. 9A and 9B, an embodiment of an actuator 64 forcontrolling a clot retrieval device 22 is shown. The actuator 64comprises a casing 70 which encircles the elongated member 16 with abutton 66 protruding from the casing's outer surface. This button 66 maybe moved proximally 68 to move the inner elongated member 16 from theextended position to the compressed position, causing the knitted basket14 to radially expand. In the embodiment shown, the button 66 is coupledto a sledge 76 which is configured to move distally within a slot 74.The sledge 76 is coupled to a stopping plate 78 which is configured tolimit the proximal motion of the button. The stopping plate 78, button66, or sledge 76 may be coupled to a grip 72 which is in turn coupled tothe elongated member 16. Relative movement between the catheter 10 andthe elongated member 16 is achieved by embedding the proximal end of thecatheter 10 within the casing 70 of the handle 64, which ensures thatthe catheter's 10 position is unchanged when the button is movedproximally or distally. Additionally, an introducer 80 may be includedon the proximal end of the handle 70 if a wire guide 21 is to beutilized. The wire guide 21 is placed within a lumen of the introducer80, which is configured to enter into a lumen of the elongated member16.

The radially expansion of the knitted basket 14 may be finely controlledby movement of the button 66 proximally or distally. If the knittedbasket 14 is being expanded within a very narrow intraluminal passage28, there may not be sufficient space to fully expand the knitted basket14. The operator may track the expansion and placement of the basket 14through a method such as fluoroscopy and use the button 66 to adjust theexpansion of the basket 14 to capture the thrombus 30 without strainingthe walls 26 of the intraluminal passage. Once captured, the thrombus 30may be partially retracted to a position within the intraluminal passage28 where the basket 14 may be fully radially expanded.

During manufacture of the device 22, it may be desirable to heat set theknitted basket 14 in the radially expanded or the radially unexpandedposition. In this way, the knitted basket 14 will exert a force toreturn to that position. If the basket 14 is heat set in the radiallyexpanded position, there may be a slight constant proximal force on thebutton 66 which the operator would have to overcome. Similarly, if thebasket 14 is heat set in the radially unexpanded position, the knittedbasket 14 may exert a slight distal force on the button 66. In such adesign, once deployed, the operator would have to exert a proximal forceto maintain the radial expansion of the knitted basket 14 and couldrelease the thrombus 30 by releasing the button 66.

Referring to FIGS. 10A-10D, another embodiment of a handle 82 foroperating a clot retrieval device 22 is shown. The handle 82 showncomprises an inner slidable member 90 and an outer sleeve 84. The outersleeve 84 encircles the elongated member 16 and has a plurality ofinwardly projecting members 92 arranged in a straight line along thelongitudinal axis of the device. The inner slidable member 90 extendsfrom the proximal end of the outer sleeve 84 and comprises a cavity 86at least large enough to accommodate the inwardly projecting members 92of the outer sleeve 84. The cavity 86 is arranged on the outer surfaceof the slidable member 90 and is defined by a region of increasedseparation between the outer surface of the slidable member 90 and theinner surface of the outer sleeve 84. The inner slidable member 90 alsocomprises at least one engaging member 94 projecting into a portion ofthe cavity 86, and at least one control surface 88 on the distal portionof the inner slidable member 90.

The outer sleeve 84 is coupled to the catheter 10 of the clot retrievaldevice 22. The inner slidable member 90 is coupled to the elongatedmember 16, so that moving the inner slidable member 90 relative to theouter sleeve 84, moves the elongated member 16 relative to the catheter10 between the extended position and the compressed position. FIGS.10A-10C show the handle 82 when the elongated member 16 is in thecompressed position. To adjust the position of the elongated member 16to the extended position, the slidable member is advanced distally.

The handle 82 allows the operator to finely adjust and lock the positionof the elongated member 16 and the radial expansion of the knittedbasket 14. The handle is in the locked position in FIG. 10C, with theelongated member in the compressed position. In this position, theinwardly projecting members 92 of the outer sleeve 84 overlap with theengaging members 94 within the cavity 86 of the inner slidable member90. To unlock the handle 82, the inner slidable member 90 may be rotatedrelative to the outer sleeve 84 so that the inwardly projecting members92 no longer overlap with the engaging member 94 within the cavity 86.In this position, the inner slidable member 90 may be advanced as needby the operator to change the position of the elongated member 16 andthe radial expansion of the knitted basket 14, as shown in FIG. 10D.Once the position is reached, the handle 82 may be locked by rotatingthe inner slidable member 90 relative to the outer sleeve 84 so that theinwardly projecting members 92 again overlap with the engaging members94 within the cavity 86.

Accordingly, it is now apparent that there are many advantages of theinvention provided herein. In addition to the advantages that have beendescribed, it is also possible that there are still other advantagesthat are not currently recognized but which may become apparent at alater time.

While preferred embodiments of the invention have been described, itshould be understood that the invention is not so limited, andmodifications may be made without departing from the invention. Thescope of the invention is defined by the appended claims, and alldevices that come within the meaning of the claims, either literally orby equivalence, are intended to embrace them.

We claim:
 1. A method of retrieving an obstruction within anintraluminal passage, comprising: inserting a retrieval device into anintraluminal passage, the retrieval device comprising an outer catheter,an elongated member extending through a lumen of the outer catheter, anda basket having a proximal end coupled to the outer catheter and adistal end coupled to the elongated member, wherein the basket comprisesa plurality of cells defined by interconnected windings of a pluralityof wires, the windings comprising one of the plurality of wires twistedabout another of the plurality of wires; positioning the basketalongside the obstruction while the basket is compressed against theelongated member; and radially expanding the basket to capture a portionof the obstruction within the basket, wherein the basket is radiallyexpanded by relative movement between the outer catheter and theelongated member.
 2. The method of claim 1, wherein when radiallyexpanding the basket, at least one of the plurality of wires passesthrough the obstruction.
 3. The method of claim 1, wherein when radiallyexpanding the basket, the portion of the obstruction passes through oneof the plurality of cells into the basket.
 4. The method of claim 3,wherein a width of at least one of the plurality of cells decreases asthe basket expands.
 5. The method of claim 1, further comprising lockingthe position of the elongated member with respect to the outer cathetersuch that the basket is maintained compressed against the elongatedmember.
 6. The method of claim 1, further comprising locking theposition of the elongated member with respect to the outer catheter suchthat the radial expansion of the basket is maintained.
 7. The method ofclaim 1, further comprising moving the basket to a position proximate anaspiration catheter after capturing the portion of the obstruction. 8.The method of claim 1, wherein the basket is knitted.
 9. The method ofclaim 1, wherein each winding is a double-twist winding.
 10. The methodof claim 1, wherein the number of twists in each winding is even. 11.The method of claim 1, wherein the number of twists in each winding isodd.
 12. The method of claim 1, wherein a distal portion of theelongated member comprises an atraumatic tip having a rounded end. 13.The method of claim 1, wherein the elongated member comprises a lumen,and the method comprises initially advancing a wire guide to a locationof the obstruction and advancing the retrieval device over the wireguide.
 14. The method of claim 1, wherein each cell of the basketcomprises four wires.
 15. The method of claim 1, wherein each cellcomprises four windings.
 16. The method of claim 1, wherein a shape ofeach cell is triangular or diamond-shaped.
 17. The method of claim 1,wherein each of the plurality of wires spirals around a circumference ofthe basket.